If HiZ enabled on any recent Mesa on a "sandybridge" platform, the Chrome browser with WebGL enabled will hang the GPU within 10-30 minutes. Not seen on "ivybridge".
To reproduce on a "sandybridge" machine:
1. Build Mesa with HiZ enabled
2. Enable WebGL in the Chrome browser
3. Log into Google Maps, and "try the new maps"
Expected result: Can enjoy WebGL web application to heart's content.
Actual result: Within 10-30 minutes, GPU hangs. Game over.

Joe,
I just landed a bunch of Sandybridge GPU hang fixes on Mesa master.
Currently we have two known GPU hangs:
- IPEHR = 0x7905 (3DSTATE_DEPTH_BUFFER)
=> bug #70151 - should be fixed with Mesa master as of today
- IPEHR = 0x0b160001 (MI_SEMAPHORE_MBOX) -
=> bug #54226 - still unsolved; a kernel issue.
Either /sys/class/drm/card0/error (modern kernels) or /sys/kernel/debug/dri/0/i915_error_state (older kernels) will tell you which issue you have. You can decode it with intel_error_decode from intel-gpu-tools. Or just attach it.
The one that I fixed apparently is much more common, and we've had other reports of Google Maps triggering it. So most likely, your bug is fixed.
Could you try master? Thanks!
--Ken

Correct.
I spoke to Carl this morning, and the plan is to skip them for 9.2.3 (which comes out this Friday) but include them in the 9.2.4 release (in about two weeks). That way, there's more time for people to test them, and make sure they don't actually cause new GPU hang issues. (Sandybridge is notoriously picky about flushing...)

Created attachment 89240[details]
intel_gpu_abrt.tar
sudo intel_gpu_abrt
No protocol specified
Can't open display :0
intel_gpu_abrt.tar has been created.
System environment:
-- chipset:
-- system architecture: x86_64
-- xf86-video-intel:
-- xserver: 1.14.4
-- mesa: 9.2.3
-- libdrm: 2.4.47
-- kernel: 3.12.0-1-ARCH
-- Linux distribution: Archlinux up-to-date
-- Machine or mobo model:
-- Display connector:
I searched bug with IPEHR number 0x7a000002, and I found this bug. The hang happened during a Hearthstone game via wine, after I installed kernel 3.12 and mesa 9.2.3 today.
This hang takes longer to recover, compared with bug #70151 to which I was also a victim. The screen doesn't simply freeze during the hanging, but rather it looks like a 30-second powerpoint slide of corrupted images.